Type member: Murine coronavirus

Contents

This is one of the genera in the subfamily Coronavirinae of the family Coronaviridae. Within this subfamily, viruses have spherical virions with club-shaped surface projections and a core shell. The name is from the Latin corona = crown, reflecting the appearance of these projections in electron microscopy. This genus contains what were previously considered phylogroup 2 coronaviruses.

Two large, overlapping ORFs at the 5'-end of the genome encode the major non-structural proteins and are expressed as a fusion protein by ribosomal frameshift. These contain regions with protease, helicase and RNA polymerase motifs. Downstream are up to 9 other genes, most of which encode structural proteins, and these are expressed from a 3'-coterminal nested set of subgenomic RNAs. The major characterised proteins occur in a conserved order and are:

Hemagglutinin-esterase protein HE (only in some members)

Spike protein S

Two to three small non-structural proteins

Small envelope protein E

Membrane protein M

Coat protein N

In some viruses there are additional small non-structural proteins between genes M and N or downstream of N